JP4855018B2 - Functional barriers in oxygen scavenging films - Google Patents

Abstract

An article of manufacture includes an oxygen scavenger, and a polymer selected from the group consisting of a polymer derived from a propylene monomer, a polymer derived from a methyl acrylate monomer, a polymer derived from a butyl acrylate monomer, a polymer derived from a methacrylic acid monomer, polyethylene terephthalate glycol (PETG), amorphous nylon, ionomer, and a polymeric blend indluding a polyterpene. The article can be in the form of e.g. a film, a polymeric functional barrier coating on an oxygen scavenging lacquer, or a gasket. A package can be made from this article for containing an oxygen-sensitive article such as food. The described polymers reduce or block the migration of odor causing by-products of an oxygen scavenging process. A method of making an article of manufacture having reduced migration of by-products of an oxygen scavenging reaction includes providing an article including an oxygen scavenger and the above-described polymer; and exposing the article to actinic radiation.

Description

  The present invention generally relates to articles and methods for capturing by-products of oxygen scavenging reactions.

  It is well known that suppressing the exposure of oxygen sensitive items to oxygen maintains and enhances the quality and shelf life of the article. In the food packaging industry, several means have already been developed to suppress exposure to oxygen.

  These means include modified air packaging (MAP) to modify the internal environment of the packaging; gas inflow; vacuum packaging; vacuum packaging using oxygen barrier packaging materials; Oxygen barrier films and laminates reduce or delay oxygen penetration from the outside environment into the package.

  Another method currently used is by “active packaging”. Inclusion of an oxygen scavenger in the cavity or interior of the package is a form of active packaging. Typically, such scavengers are in the form of a sachet containing a composition that scavenges oxygen by chemical reaction. One type of packet contains an iron composition that is oxidized. Another type of wrap contains unsaturated fatty acid salts on the particulate adsorbent. Yet another type of wrap contains metal / polyamide complexes as disclosed in WO 88/06641.

One drawback of wrapping is that another wrapping operation is required to add the wrap to each package. Another drawback arising from the bag is that certain air conditions (eg, high humidity, low CO ₂ levels) in the package are necessary for capture to occur at an appropriate rate.

  Another means of suppressing exposure to oxygen is to introduce an oxygen scavenger into the packaging structure itself. This achieves a more uniform capture effect within the package. This can be particularly important when air circulation is suppressed in the package. In addition, this introduction blocks and captures oxygen as it passes through the walls of the package (referred to herein as an “active oxygen barrier”), thereby reducing the oxygen level as low as possible within the package. Can be provided.

  One attempt to produce an oxygen scavenging wall involves the introduction of inorganic powders and / or salts. However, the introduction of these powders and / or salts results in a decrease in physical properties such as wall transparency and tear strength. Furthermore, these compounds can cause processing difficulties, in particular processing difficulties in the production of thin films or thin layers in the film structure. Furthermore, the capture rate of the walls containing these compounds is unsuitable for certain commercially available oxygen scavenging applications, such as applications using wrapping.

  Other efforts have been directed to introducing a metal catalyst-polyamide oxygen scavenging system within the packaging wall. However, this system does not show oxygen scavenging at a commercially available rate.

  An oxygen scavenger suitable for commercial use in the film of the present invention is disclosed in US Pat. No. 5,350,622, and a method for initiating oxygen scavenging is generally disclosed in US Pat. No. 5,211,875. Yes. Both patents are hereby incorporated by reference in their entirety. According to US Pat. No. 5,350,622, oxygen scavengers are made from ethylenically unsaturated hydrocarbons and transition metal catalysts. Suitable ethylenically unsaturated hydrocarbons may be substituted or unsubstituted. As defined herein, an unsubstituted ethylenically unsaturated hydrocarbon is a compound having at least one aliphatic carbon-carbon double bond and containing 100 wt% carbon and hydrogen. Substituted ethylenically unsaturated hydrocarbon is defined herein as an ethylenically unsaturated hydrocarbon having at least one aliphatic carbon-carbon double bond and containing about 50-99 wt% carbon and hydrogen. To do. Suitable substituted or unsubstituted ethylenically unsaturated hydrocarbons are those having 2 or more ethylenically unsaturated groups per molecule. More preferably, it is a polymerized compound having 3 or more ethylenically unsaturated groups and a weight average molecular weight of 1,000 or more.

  Suitable examples of unsubstituted ethylenically unsaturated hydrocarbons include diene polymers such as polyisoprene (eg trans-polyisoprene) and copolymers thereof, cis and trans 1,4-polybutadiene, 1,2-polybutadiene (50% Defined as polybutadiene having the above 1,2 microstructure), and copolymers thereof such as, but not limited to, styrene-butadiene copolymers. Such hydrocarbons also include polymer compounds such as polypentenamers, polyoctenamers and other polymers produced by cyclic olefin metathesis; diene oligomers such as squalene; and dicyclopentadiene, norbornadiene, 5-ethylidene-2-norbornene, There are unsaturated polymers or copolymers derived from 5-vinyl-2-norbornene, 4-vinylcyclohexene, 1,7-octadiene or other monomers containing two or more carbon-carbon double bonds (conjugated or non-conjugated).

  Suitable substituted ethylenically unsaturated hydrocarbons include but are not limited to those having oxygen-containing moieties such as esters, carboxylic acids, aldehydes, ethers, ketones, alcohols, peroxides and / or hydroperoxides. Specific examples of such hydrocarbons include condensation of monomers containing carbon-carbon double bonds with unsaturated fatty acids such as oleic acid, lesinolic acid, dehydrated lesinolic acid, linolenic acid and derivatives thereof such as esters. There are polymers, but not limited to them. Such hydrocarbons also include polymers or copolymers derived from (meth) allyl (meth) acrylates. Suitable oxygen scavenging polymers can be made by trans-esterification. Such polymers are disclosed in WO 95/02616, which is hereby incorporated by reference in its entirety. The composition used also includes a mixture of two or more of the above substituted or unsubstituted ethylenically unsaturated hydrocarbons. A weight average molecular weight of 1,000 or more is preferred, but lower molecular weight ethylenically unsaturated hydrocarbons can also be used if they are mixed with a film-forming polymer or mixture of polymers.

  It will also be apparent that ethylenically unsaturated hydrocarbons suitable for forming a transparent layer that is solid at room temperature are preferred for oxygen scavenging in the packaging articles described above. For most applications where transparency is required, a layer capable of transmitting at least 50% of visible light is preferred.

  When preparing the transparent oxygen scavenging layer of the present invention, 1,2-polybutadiene is particularly preferred for use at room temperature. For example, 1,2-polybutadiene can exhibit transparency, physical properties and processing properties similar to polyethylene. Furthermore, the polymer has been found to remain transparent and physically complete even after most or all of the oxygen uptake capacity has been lost and even when little or no diluent resin is present. ing. Furthermore, 1,2-polybutadiene exhibits a relatively high oxygen uptake capacity and, when it begins to capture, also exhibits a relatively high capture rate.

  When low temperature oxygen scavenging is desired, 1,4-polybutadiene, styrene and butadiene copolymers, and styrene and isoprene copolymers are particularly preferred. Such compositions are disclosed in US Pat. No. 5,310,497, issued Speer et al., May 10, 1994, which is hereby incorporated by reference in its entirety. In many cases, it is desirable to mix the polymer with an ethylene polymer or copolymer.

  Other oxygen scavengers that can be used in connection with the present invention include US Pat. Nos. 5,075,362 (Hofeldt et al.), 5,106,886 (Hofeldt et al.), 5,204,389 (Hofeldt et al.), And No. 5,227,411 (Hofeldt et al.) [All of these patents are incorporated herein by reference in their entirety]. These oxygen scavengers can be ascorbate or isoascorbate or a mixture with each other or with sulfites, often sodium sulfite.

  Still other oxygen scavengers that can be used in connection with the present invention include PCT patent applications WO 91/17044 (Zapata Industries), WO 94/09084 (Aquanautics Corporation) and WO 88/066641, all of which are hereby incorporated by reference in their entirety. It shall be disclosed. These oxygen scavengers include transition metal catalyst-containing ascorbates. Here, the catalyst is a simple metal of a transition metal itself, or a salt thereof, or a compound, complex or chelate; or a transition metal complex or chelate of polycarboxylic acid, salicylic acid or polyamine (in some cases, a reducing agent such as ascorbate) The transition metal complex or chelate mainly acts as an oxygen scavenging composition.

  Still other oxygen scavengers that can be used in connection with the present invention are disclosed in PCT Patent Publication WO 94/12590 (Commonwealth Scientific and Industrial Research Organization), which is hereby incorporated by reference in its entirety. These oxygen scavengers include at least one reducing organic compound that is reduced under predetermined conditions, wherein the reduced form of the compound is oxidizable by oxygen molecules, and the reduction of the organic compound and / or Alternatively, there are such compounds characterized in that subsequent oxidation occurs independently of the presence of the transition metal catalyst. Preferably, the reducing organic compound is a quinone, a photoreducing dye, or a carbonyl compound having absorption in the UV spectrum.

  Sulfites, alkali metal sulfites, and tannins are also considered oxygen scavenging compounds.

  As described above, the ethylenically unsaturated hydrocarbon is combined with a transition metal catalyst. Without being bound by theory, the inventors have observed that suitable metal catalysts can be easily converted to at least two oxidation states. See Sheldon, R.A., Kochi, J.K., “Metal-Catalyzed Oxidations of Organic Compounds” Academic Press, New york 1981.

  Preferably, the catalyst is in the form of a transition metal salt. Here, the metal is selected from the first, second or third transition series of the periodic rate table. Suitable metals include, but are not limited to, manganese II or III, iron II or III, cobalt II or III, nickel II or III, copper I or II, rhodium II, III or IV, and ruthenium II or III. Not. The oxidation state of the metal when introduced does not necessarily have to be that of the active form. Preferably the metal is iron, nickel or copper, more preferably manganese, most preferably cobalt. Suitable counter ions for metals are chloride ion, acetate ion, stearate ion, palmitate ion, caprylate ion, linoleate ion, tallate ion, 2-ethylhexanoate ion, neodecanoate ion, oleate ion Or naphthenate ions, but not limited to. Particularly suitable salts are cobalt (II) 2-ethylhexanoate, cobalt stearate and cobalt (II) neodecanoate. Metal salts can also be ionomers. In that case, a polymeric counter ion is used. Such ionomers are well known in the art.

  The ethylenically unsaturated hydrocarbon and transition metal catalyst can be further combined with one or more polymer diluents, such as thermoplastic polymers typically used to form film layers in plastic packaging articles. In the manufacture of certain packaging products, well-known thermosetting materials can also be used as polymer diluents.

  Polymers that can be used as diluents include polyethylene terephthalate (PET), polyethylene, low density or very low density polyethylene, ultra low density polyethylene, linear low density polyethylene, polypropylene, polyvinyl chloride, polystyrene, and ethylene-vinyl acetate, There are ethylene copolymers such as, but not limited to, ethylene-alkyl (meth) acrylates, ethylene- (meth) acrylic acid and ethylene- (meth) acrylic acid ionomers. Mixtures of different diluents can also be used. However, as noted above, the choice of polymer diluent depends primarily on the product being manufactured and the end use. Such selection factors are well known in the art.

  Additional additives can also be included in the composition to provide the desired properties for the particular product being manufactured. Such additives include, but are not limited to, fillers, pigments, dyes, antioxidants, stabilizers, processing aids, plasticizers, flame retardants, antifoaming agents and the like.

  Preferably, the mixing of the components is performed by melt mixing at a temperature in the range of 50-300 ° C. However, alternative methods such as the use of a solvent followed by evaporation can also be used. Mixing can occur immediately prior to manufacture of the final product, or prior to manufacture of raw materials or masterbatches for later use in the manufacture of the final packaging article.

  While these technologies offer great potential in packaging applications, sometimes oxygen scavenging structures can affect the taste and odor (ie, sensory properties) of the packaged material or create food regulatory issues. It has been found that possible reaction by-products can be produced. These by-products include organic acids, aldehydes, and ketones.

  This problem can be minimized by the use of a polymeric functional barrier. A polymeric functional barrier is a polymeric material that acts as a selective barrier to by-products from the oxygen scavenging reaction, but is not itself a significant barrier to oxygen. The functional barrier is selected from the group consisting of one or more of the following: propylene monomer-containing polymer, methyl acrylate monomer-containing polymer, methacrylic acid monomer-containing polymer, polyethylene terephthalate glycol (PETG), amorphous nylon, ionomer, And a polymer mixture containing polyterpenes. Such a functional barrier polyterpene mixture is disclosed in Balloni et al., WO 94/06626, which is hereby incorporated by reference in its entirety. Examples include, but are not limited to, polypropylene, propylene / ethylene copolymers, ethylene / methacrylic acid copolymers, and ethylene / methyl acrylate copolymers. Functional barrier polymers can be further mixed with other polymers to modify the oxygen permeability required for certain applications. The functional barrier can be introduced into one or more layers or containers of a multilayer film that includes an oxygen scavenging layer. However, one skilled in the art will readily appreciate that the present invention is applicable to any oxygen scavenging system that produces by-products such as organic acids, aldehydes, ketones and the like.

  Polymeric functional barriers for oxygen scavenging applications are disclosed in Ching et al., WO 96/08371, which is hereby incorporated in its entirety. The material in this case is preferably a glassy polymer with a high glass transition temperature (Tg), such as further stretched polyethylene terephthalate (PET) and nylon 6. In contrast, the inventors of the present application surprisingly found that certain low Tg polymers and mixtures thereof are useful functional barrier materials.

In certain applications of oxygen scavenging, it is desirable to rapidly scavenge oxygen from the packaging headspace. In order to do this, the functional barrier layer has a relatively high permeability to oxygen, but must maintain the property of a functional barrier (ie prevent migration of small organic molecules). In these cases, the oxygen permeability of the functional barrier is preferably greater than about 3,000 cc O ₂ / m ² / day / atm (tested at 1 mil thickness and 25 ° C.), but preferably greater than 5,000 More preferably greater than 8,000 and optimally greater than 10,000 cc O ₂ / m ² / day / atm (tested at ASTM D3985 at 1 mil thickness and 25 ° C.). The higher the permeability of the layer sandwiched between the package oxygen scavenger and the headspace, the faster oxygen can be captured from the headspace. The exact oxygen permeability required for a given application can be readily determined by experimentation by one skilled in the art. By mixing a functional barrier polymer with a polymer having a fairly high oxygen permeability, higher oxygen permeability can be easily achieved. Polymers useful for blending with the functional barrier polymer include, but are not limited to, alkyl acrylate polymers and copolymers, particularly ethylene / butyl acrylate copolymers, ethylene / vinyl acetate copolymers, and the like.

Definitions “Film” as used herein means a film, laminate, sheet, web, coating, etc. that can be used to package an object.

  As used herein, “oxygen scavenger” (OS), etc. means a composition, article, etc. that consumes, depletes, or reacts with oxygen from an environment.

  “Actinic radiation” as used herein refers to ultraviolet radiation or electron beam disclosed in US Pat. No. 5,211,875 (Speer et al.), Which is hereby incorporated by reference in its entirety. Means any type of radiation, such as radiation.

  By “functional barrier” herein is meant a polymeric material that acts as a selective barrier to by-products from oxygen scavenging reactions rather than oxygen.

  As used herein, “LLDPE” means linear low density polyethylene, which is an ethylene / α-olefin copolymer.

  As used herein, “EVOH” means an ethylene / vinyl alcohol copolymer.

  As used herein, “EVA” means an ethylene / vinyl acetate copolymer.

  As used herein, “polymer” and the like also refer to copolymers including homopolymers, bispolymers, terpolymers and the like.

“Ethylene / α-olefin copolymer” and the like in this specification include linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE) and ultra low density polyethylene and ultra low density polyethylene (VLDPE and ULDPE). Homogeneous materials; and homogeneous polymers such as metallocene catalyzed polymers such as EXACT ^™ supplied by Exxon and TAFMER ^™ material supplied by Mitsui Petrochemical Co., Ltd. These materials are generally copolymers of ethylene and one or more comonomers selected from C _{4 to} C ₁₀ α-olefins such as butene-1 (ie 1-butene), hexene-1, octene-1, etc. The copolymer molecule is a copolymer characterized by having a long chain with relatively few side chain branches or crosslinked structures. This molecular structure should be in contrast to normal low or medium density polyethylenes that are more branched than the corresponding ones. Other ethylene / α-olefin copolymers, such as the long chain branched homogeneous ethylene / α-olefin copolymer known as AFFINITY ^™ resin, commercially available from Dow Chemical, are other ethylene / α-olefin copolymers useful in the present invention. Include as a type. It is further contemplated that single site catalyzed polyethylene referred to as Versipol ^™ (DuPont) is useful in the present invention.

  The term “polyamide” as used herein refers to a polymer having an amide bond in the molecular chain, preferably a synthetic polyamide such as nylon. In addition, such terms include polymers containing repeat units derived from monomers such as caprolactam that polymerize to form polyamides and nylon terpolymers, also commonly referred to herein as “copolyamides”. Includes both copolymers of more than one amide monomer.

SUMMARY OF THE INVENTION In one aspect of the invention, an article comprises an oxygen scavenger, a polymer derived from a propylene monomer, a polymer derived from a methyl acrylate monomer, a polymer derived from butyl acrylate, a polymer derived from a methacrylic acid monomer, polyethylene terephthalate glycol. (PETG), an amorphous nylon, an ionomer, and a polymer selected from the group consisting of polymer mixtures containing polyterpenes.

  In a second aspect of the invention, the packaging contains oxygen sensitive articles, as well as oxygen sensitive articles, oxygen scavenger containing layers and polymers derived from propylene monomers, polymers derived from methyl acrylate monomers, polymers derived from butyl acrylate. A container comprising a component containing a layer containing a polymer selected from the group consisting of: a polymer derived from methacrylic acid monomer, polyethylene terephthalate glycol (PETG), amorphous nylon, ionomer, and a polymer mixture containing polyterpene.

  In a third aspect of the present invention, a method for producing an article with reduced by-product transfer of oxygen scavenging reactions comprises an oxygen scavenger-containing layer and a polymer derived from propylene monomer, a polymer derived from methyl acrylate monomer, acrylic acid Provided is an article comprising a layer containing a polymer selected from the group consisting of polymers derived from butyl, polymers derived from methacrylic acid monomers, polyethylene terephthalate glycol (PETG), amorphous nylon, ionomers, and polyterpenes. And exposing the article to actinic radiation.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS . 1-5 are schematic cross-sectional views of various embodiments of the film of the present invention, so that the invention can be further understood based on the drawings.
Figures 6-11 graphically illustrate the acetaldehyde concentration versus time for various films of the present invention and comparative examples.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be used to produce various articles, compounds, compositions of matter, coatings, and the like. Three suitable types are sealing compounds (mixtures) or gaskets; polymeric functional barrier coatings on oxygen scavenging lacquers; and flexible films; all useful for packaging food and non-food items .

  The use of sealing mixtures in the manufacture of gaskets for the rigid container market is known. Typically, large, large diameter gaskets are manufactured using liquid plastisols. This plastisol is a very viscous liquid suspension of polymer particles in a plasticizer. In the production of metal or plastic caps, lids, etc., this liquid plastisol is applied to the ring of a container such as a jar, and the container with the applied plastisol is “melted” in an oven, which solidifies the plastisol into a gasket. . The result is a gasket formed around the ring of the container.

  Typically, smaller gaskets are manufactured for use in beer bottle crowns. The dissolved polymer is applied by cold molding to the entire inner surface of the crown. Both PVC and other polymers are used in this application.

  Typically, a plastic cap disc is manufactured by using a ribbon of gasket material, manufacturing the disc, and inserting the disc into a plastic cap.

  In all of these applications, the use of oxygen scavengers and polymeric functional barriers advantageously removes oxygen from the vessel's internal environment, while suppressing unwanted by-products of the oxygen scavenging reaction.

  That is, the gasket includes an oxygen scavenger and a polymeric functional barrier. The gasket attaches a metal or plastic lid or cap to a hard or semi-hard container and seals the container with the lid or cap.

  Lacquers for cans or rigid or semi-rigid containers can include oxygen scavenging materials, such as those of the type described herein, and can be coated with a polymeric functional barrier.

  The films of the present invention can be produced by conventional means such as coextrusion, lamination, extrusion coating, solution coating, or corona bonding, optionally irradiation and / or stretching. The film of the present invention can be made heat shrinkable by stretching or transverse stretching, if desired, at a stretch ratio of 1: 2 to 1: 9 in either the machine direction or the transverse direction, or both. For shrinkage applications, the film of the present invention has a free shrinkage in either or both directions at 90 ° C. of at least 10%, more preferably at least 20%, optimally at least 30%. Can be manufactured. The polymeric functional barrier can be used in two or more layers of a multilayer film. Different polymeric functional barriers can be used in the same film. The polymeric functional barrier is used in the film and as a packaging material so that the polymeric functional barrier is positioned closer to the contents of the package, which may be a food or oxygen sensitive article, than the oxygen scavenger. Although preferred, there may also be applications where the polymeric functional barrier is positioned “outside” the oxygen scavenger so that the oxygen scavenger is positioned closer to the contents of the package than the polymeric functional barrier. Polymeric functional barriers can also be placed on both sides of the oxygen scavenger.

  Alternatively, in addition to or instead of the arrangements described elsewhere herein, the functional barrier can be arranged in the same layer (s) as the oxygen scavenger material. By way of example, any of 14, 34, 44, 54 in the examples and figures can include a functional barrier in any suitable percent of the layer weight. Any suitable polymeric material can be used in the functional barrier-containing film and is not limited to those described herein.

  The polymeric functional barriers disclosed herein can be used with or in a film or coating, or as a coating on a layer or another object, such as a bottle cap or bottle liner, Variety for capture or other applications such as glued or non-bonded inserts, sealants, gaskets, fibrous mats or other inserts, or non-essential components of hard, semi-hard or soft containers Other substrates can be absorbed or adsorbed onto the substrate.

  In FIG. 1, a multilayer film 10 having layers 12 and 14 is shown.

  FIG. 2 shows a multilayer film having layers 12, 14, 16. Preferably, layers 12, 14, 16 are polymers.

  Layer 12 contains a polymer derived from propylene monomer, a polymer derived from methyl acrylate monomer, a polymer derived from butyl acrylate, a polymer derived from methacrylic acid monomer, polyethylene terephthalate glycol (PETG), amorphous nylon, ionomer, and polyterpene. Contains a polymer selected from the group consisting of polymer mixtures. These materials can act as a functional barrier against the migration or extraction of by-products of the oxygen scavenging reaction that occurs in the film.

  Layer 14 is an oxygen scavenger, preferably a polymeric oxygen scavenger, more preferably one of the above materials.

  Layer 16 includes an oxygen barrier material such as ethylene vinyl alcohol copolymer (EVOH), saran (vinylidene chloride copolymer), polyester, polyamide, metal, silica coating, and the like.

  FIG. 3 shows a laminated film in which a three-layer film is adhered to a second film. Layers 32, 34, 36 functionally and compositionally correspond to 12, 14, 16 in FIG. 2, respectively, and layer 38 is a polymeric material such as a polyolefin, more preferably ethylene / α-olefin and ethylene / polyethylene. Any polymeric material interlayer that may comprise an ethylenic polymer such as a saturated ester copolymer, more preferably an ethylene / vinyl acetate copolymer. Layer 31 represents a conventional adhesive such as a polyurethane adhesive. Comparison 2 in Table 6 is an example of the laminated film of FIG.

FIG. 4 shows a laminated film in which a four-layer film is bonded to a second film. Layers 42, 44, 46, 48 functionally and compositionally correspond to 32, 34, 36, 38 in FIG. 3, respectively. Layer 49 is an innermost heat sealable layer that may include any polymeric material such as polyolefins, more preferably ethylenic polymers such as ethylene / α-olefins and ethylene / unsaturated ester copolymers such as ethylene vinyl acetate copolymers. . Layer 46 provides an oxygen barrier to the film structure and adheres to layer 48 with conventional adhesive 41. This adhesive corresponds to the layer 31 in FIG. 3 and is simply represented as a thick line. Reference examples 2 and 3 in Table 6 are examples of the laminated film of FIG.

FIG. 5 shows a 9-layer film. Reference Example 1 and Comparative Example 1 in Table 2 are examples of the film in FIG.

  Layer 57 is an abuse resistant layer useful as the outermost layer of the film when used in packaging applications.

  Layers 54 and 56 functionally correspond to layers 14 and 16 of FIGS. 2 and 3, respectively, and layers 44 and 46 of FIG. 4, respectively.

  Layers 52, 53, 58, 59 contain an adhesive. Preferably the adhesive is a polymer, more preferably a polyolefin grafted with an acid or acid anhydride. In addition, these layers may include a polymeric functional barrier of the type described for layer 12.

  Layer 55 includes a heat resistant material. This can be any suitable polymeric material, preferably an amide polymer such as nylon 6, or a polyester such as polyethylene terephthalate. Layer 55 may include a polymeric functional barrier of the type described for layer 12.

  Layer 51 includes a heat sealable material. This can be any suitable polymeric material, preferably an olefinic polymer such as an ethylenic polymer, more preferably an ethylene alpha-olefin copolymer.

6 to 11, each of the horizontal “X” axis represents time (minutes), and the vertical “Y” axis represents acetaldehyde migration (unit representing the area under the curve of the peak section of the gas chromatograph) of the reference example. Indicates.

In FIG. 6, the curve plotted with the diamond symbol represents the acetaldehyde migration over time through the film of Reference Example 1. The curve plotted by the square symbol represents the migration of acetaldehyde over time through the film of Reference Example 2. The curve plotted by the triangle symbol represents the migration of acetaldehyde over time through the film of Reference Example 3.

Similarly to the above, in FIG. 7, the diamond symbol represents Reference Example 4, the square symbol represents Reference Example 5, and the triangle symbol represents Reference Example 6.

In FIG. 8, the hollow square symbol represents Reference Example 7, the non-hollow (black) square symbol on the dotted line represents Comparative Example 1, the hollow triangular symbol represents Reference Example 8, and the non-hollow ( Black) The triangle symbol represents Comparative Example 2.

In FIG. 9, the square symbol represents Reference Example 9, the triangle symbol represents Reference Example 10, and the dotted line represents Comparative Example 3.

In FIG. 10, the square symbol represents Reference Example 11, the triangle symbol represents Reference Example 12, and the dotted line represents Comparative Example 4.

In FIG. 11, the diamond symbol represents Reference Example 13, the square symbol represents Reference Example 14, the triangle symbol represents Reference Example 15, the asterisk symbol represents Reference Example 16, and the dotted line represents Comparative Example 5. To express.

The invention can be further understood by reference to the following reference examples . Table 1 identifies the substances used in the reference examples .

In some cases of film structure, certain materials were mixed together, and these mixtures are identified as follows:
OSB ₁ = 60% OS ₁ + 38.93% EV ₁ + 1.06% CAT ₁ + 0.01% Irganox 1076 (antioxidant)
OSB ₂ = 60% OS ₁ + 39.2% EV ₁ + 0.5% EV ₃ + 0.3% CAT ₂
OSB ₃ = 76.5% OS ₂ + 13.5% OS ₃ + 9.2% EV ₁ + 0.5% PI ₁ + 0.3% CAT ₂
OSB ₄ = 40% OS ₁ + 54.83% EV ₁ + 1.06% CAT ₁ + 0.10% PI ₂ + 0.01% Irganox 1076 (antioxidant)
PEB ₁ = 85% PE ₁ + 15% PT ₁
PEB ₂ = 90% PE ₂ + 10% AB ₁
EVB ₁ = 85% EV ₁ + 15% PT ₁
IONB ₁ = 90% ION ₃ + 10% AB ₁
PPB ₁ = 60% PP ₂ + 40% EB ₂
PPB ₂ = 40% PP ₂ + 60% EB ₂

  It has been found that oxygen scavenging structures can produce reaction by-products that can affect the taste and odor of the packaged material or can cause food regulatory issues. These by-products include aldehydes, acids, ketones and the like. An aldehyde migration test was developed to confirm the potential of a functional barrier. In this test, acetaldehyde was selected as a model aldehyde compound because it was relatively mobile. A film sample was sandwiched between each two halves of a cell with one clamp and two O-rings. Acetaldehyde was introduced on the half side of the cell. Using a gas chromatograph, the concentration of acetaldehyde transferred through the film sample to the other half of the cell was measured. The functional barrier can significantly reduce acetaldehyde migration through the film sample. Table 2 discloses three monolayer films.

  The target (and near actual) dimension for each monolayer was 2 mil. The migration of acetaldehyde through the film is shown in FIG. Polypropylene is considered a functional barrier.

  Table 3 discloses three monolayer films.

  The target (and near actual) dimension for each monolayer was 2 mil. The migration of acetaldehyde through the film is shown in FIG. Polypropylene and propylene-ethylene copolymers are considered functional barriers.

  Table 4 discloses two single layer films and two comparative single layer films.

  The target (and near actual) dimension for each monolayer was 2 mil. The acetaldehyde migration through the film is shown in FIG. Mixing small amounts of polyterpenes with other polymers can increase the functional barrier properties of certain polymers.

  Table 5 discloses two co-extruded 4-layer films of the present invention and a comparative 4-layer film.

  The target (and almost actual) dimensions (in the mill) of each layer of the structure compared to the present invention were as follows:

  During the acetaldehyde transfer test, the oxygen scavenging reaction was not activated. The migration of acetaldehyde through the film is shown in FIG. Ethylene-methyl acrylate copolymers and ethylene-methyl acrylate-methacrylic acid terpolymers are considered functional barriers.

  Table 6 discloses two coextruded four layer films of the present invention and a comparative four layer film.

  The target (and almost actual) dimensions (in the mill) of each layer of the structure compared to the present invention were as follows:

  During the acetaldehyde transfer test, the oxygen scavenging reaction was not activated. The migration of acetaldehyde through the film is shown in FIG. Ionomers based on ethylene-methyl acrylate copolymers are considered functional barriers.

  Table 7 discloses four coextruded three layer films of the present invention and a comparative three layer film.

  The target (and almost actual) dimensions (in the mill) of each layer of the structure compared to the present invention were as follows:

  During the acetaldehyde transfer test, the oxygen scavenging reaction was not activated. The migration of acetaldehyde through the film is shown in FIG. Ethylene-methacrylic acid copolymers are considered functional barriers.

  Table 8 discloses three 9-layer films of the present invention and comparative examples. Each of these is manufactured by coextrusion of the layers.

  The target (and almost actual) dimensions (in the mill) of each layer of the 9-layer film structure are shown below. Preferably, layer 9 is a food or article contact layer in typical packaging applications.

In order to evaluate whether the functional barrier can reduce the concentration of extractables, a food method migration test was performed on the films of Reference Examples 17, 18, 19 and Comparative 6. The film was irradiated with ultraviolet rays by the method disclosed in US Pat. No. 5,211,875. The film was made into a 280 cm ² bag, and a food mimic was placed in the bag. Next, the filled bag was kept at 100 ° C. for 30 minutes and stored at 50 ° C. for 10 days. Food mimics were removed from the bags and analyzed. Table 9 shows a list of possible extractables. Table 10 shows the concentration of the same extractables when the film was extracted with 8% ethanol solution. Table 11 shows the concentration of the same extractables when the film is extracted with water. In both Tables 10 and 11, the concentration of each extractable substance is in units of ng / mL. Functional barriers such as polyethylene terephthalate glycol and amorphous nylon can reduce the concentration of certain extractables that can cause regulatory problems.

  Table 12 discloses a four layer laminate structure of the present invention and one type of comparative four layer laminate structure. A four-layer structure was produced by laminating a co-extruded three-layer film on a second film (= layer 4) using a normal adhesive.

  The target (and nearly actual) dimensions (in the mill) of each layer of the laminate structure compared to the present invention were as follows.

Sliced Bologna sausages were stored in packaging made from the films of Reference Example 20 and Comparative 7. To assess whether the functional barrier can reduce off-flavors due to oxygen scavenging by-products, the sensory panel tasted Bologna sausage slices.

The film was irradiated with ultraviolet light by the method disclosed in US Pat. No. 5,211,875. The film was packaged with a Mulrivac® R7000 packaging machine. Cryovac® T6070B film was used as the bottom web of the package. Each package contained one slice of Bologna sausage. A mixed gas consisting of 99% N ₂ and 1% O ₂ was allowed to flow into each package. The packaging was stored in the dark at 40 ° F. for 7 days.

  The sensory panel evaluated the taste of Bologna sausage slices. The scale was 1-6, with 1 indicating very off-flavor and 6 indicating no off-flavor. Average scores are summarized in Table 13. Functional barriers such as ionomers can reduce off-flavors due to by-products of the oxygen scavenging reaction.

  Table 14 discloses the five-layer laminate structure of the present invention and one comparative five-layer laminate structure. Each of the five-layer structures was manufactured by laminating a co-extruded four-layer film on a second film (= layer 5) using a conventional adhesive.

  The target (and nearly actual) dimensions (in the mill) of each layer of the laminate structure compared to the present invention were as follows.

Sliced turkeys were stored in packaging made from the films of Reference Example 21 and Comparative 8. To assess whether the functional barrier can reduce off-flavor due to by-products of the oxygen scavenging reaction, the sensory panel tasted turkey slices.

The film was irradiated with ultraviolet light by the method disclosed in US Pat. No. 5,211,875. The film was packaged with a Mulrivac® R7000 packaging machine. Cryovac® T6070B film was used as the bottom web of the package. Each package contained one slice of turkey. A mixed gas consisting of 99% N ₂ and 1% O ₂ was allowed to flow into each package. The packaging was stored in the dark at 40 ° F. for 7 days.

  The sensory panel evaluated the taste of turkey slices. The scale was 1-6, with 1 indicating very off-flavor and 6 indicating no off-flavor. Average scores are summarized in Table 15. Functional barriers such as ethylene-methyl acrylate copolymers can reduce off-flavors due to by-products of the oxygen scavenging reaction.

  Table 16 discloses the two five-layer laminate structures of the present invention and one comparative five-layer laminate structure. Each of the five-layer structures was manufactured by laminating a co-extruded four-layer film on a second film (= layer 5) using a conventional adhesive.

  The target (and nearly actual) dimensions (in the mill) of each layer of the laminate structure compared to the present invention were as follows.

Sliced turkeys were stored in packaging made from the films of Reference Examples 22, 23 and Comparative 9. To assess whether the functional barrier can reduce off-flavor due to by-products of the oxygen scavenging reaction, the sensory panel tasted turkey slices.

The film was irradiated with ultraviolet light by the method disclosed in US Pat. No. 5,211,875. The film was packaged with a Mulrivac® R7000 packaging machine. Cryovac® T6070B film was used as the bottom web of the package. Each package contained one slice of turkey. A mixed gas consisting of 99% N ₂ and 1% O ₂ was allowed to flow into each package. The packaging was stored in the dark at 40 ° F. for 7 days.

  The sensory panel evaluated the taste of turkey slices. The scale was 1-6, with 1 indicating very off-flavor and 6 indicating no off-flavor. Table 17 summarizes the percentage of panelists who did not perceive off-flavor (ie, scored 6) in packaged turkey slices. In some cases, functional barriers such as polypropylene blends can reduce off-flavor due to by-products of the oxygen scavenging reaction.

  Various changes and modifications can be made without departing from the scope of the following claims.

It is typical sectional drawing of one embodiment of the film of this invention. It is typical sectional drawing of one embodiment of the film of this invention. It is typical sectional drawing of one embodiment of the film of this invention. It is typical sectional drawing of one embodiment of the film of this invention. It is typical sectional drawing of one embodiment of the film of this invention. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically. The acetaldehyde concentration versus time for the various films of the present invention and comparative examples is shown graphically.

Claims (2)

  An article in the form of a gasket comprising an oxygen scavenger and a polymer selected from the group consisting of polyethylene terephthalate glycol (PETG) and amorphous nylon. Oxygen scavenger
i) an oxidizing compound and a transition metal catalyst,
ii) ethylenically unsaturated hydrocarbons and transition metal catalysts,
iii) ascorbate,
iv) isoascorbate,
v) sulfite,
vi) transition metal catalysts and ascorbates, including simple metals or salts or compounds, complexes or chelates of transition metals,
vii) transition metal complexes or chelates of polycarboxylic acids, salicylic acids or polyamines,
viii) reduced quinones having absorption in the UV spectrum, photoreducible dyes or carbonyl compounds, and
The article according to claim 1, comprising a substance selected from the group consisting of ix) tannins.

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